Although talker-specific properties of speech are extremely informative to the listener, differences in the way speech is produced also create enormous variability in spoken language. During the perception of speech, listeners somehow contend with this variability, extracting the same linguistic content even when it occurs in a variety of different forms. Most models of spoken language processing assume that variation due to differences among talkers is discarded by the listener during speech perception. The end product of this normalization process is assumed to be a series of abstract, context-free linguistic units. In contrast, alternative accounts propose that listeners contend with variability by retaining specific aspects of each talker's voice. Retaining rather than discarding these perceptual properties of speech enables listeners to customize their perceptual processing for each individual talker. The purpose of the proposed research is to investigate how listeners perceptually adapt over time to specific non-linguistic characteristics of talkers' voices. Studies are proposedthat examine how listeners adapt to variation introduced by individual talkers' voices and to systematic variation introduced by accentedness. A voice-learning paradigm in which listeners are familiarized with non-linguistic properties of speechover several days of training will be used to compare and contrast the processes involved in talker-specific and accent-general perceptual compensation. The experiments will address the general hypothesis that perception learning of "nonlinguistic" dimensions of spoken language can change the nature of linguistic representation and processing. Given the diversity and variety of conversational partners that are typically encountered in today's society, research designed to evaluate how listeners cope with differences in speaking style and accent becomes imperative. Investigating the process by which listeners accommodate perceptually to differences among speakers, as well as to synthetic and pathological speech, will have important implications for maximizing effective spoken communication in work and learning environments.